My design is 2.5Ghz, so via length is critical.
Sean James
PCB Designer
Telecast Fiber Systems, Inc.
102 Grove Street
Worcester, MA 01605
(TEL) 508.754.4858 x33
(FAX) 413.541.6170
----- Original Message -----
From: "Mike Reagan" <[EMAIL PROTECTED]>
To: "Protel EDA Forum" <[EMAIL PROTECTED]>
Sent: Tuesday, November 27, 2001 12:39 PM
Subject: Re: [PEDA] Vias & trace length


>
>
>
> Is there any way to get Protel to add vias to an overall trace length? Ex.
A
> via going from top to bottom thru an .062" board would add .062" to a
total
> trace length (PCAD/ACCEL does this).
>
> Sean,
> I don't think .062 inch for any digital signal under 500 mhz makes any
> difference.  The actual capacitance of the via will pose more of a problem
> than the trace length.   Actual measurements made by Bill Brooks
> www.ultracad.com  and contributing editor to PCD magazine shows no
relevant
> impedance changes with vias placed in a trace.  There are little hic-cups
in
> the impedance but it really doesn't change much.   I wish protel would
give
> me a calculation of the capacitance with the via included.   A trace
length
> is irrelevant unless it approaches a critical length for the signal, but
> loss can become a  bigger factor.
> Question;   Why don't you use Acell PCAD?    personally I think it sucks
>
>
> Mike Reagan
> EDSI
> Frederick MD
>

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